Control Electronics for Brushless Motors

Abstract

An electronic control circuit for a brushless motor has an input power circuit providing a DC voltage and a microcontroller integrated circuit receiving the DC voltage. The microcontroller integrated circuit provides three-phase control signals according to a space vector control method. A microprocessor connected to the microcontroller integrated circuit executes supervisory control over the electronic control circuit. An inverter circuit receives the three-phase control signals from the microcontroller integrated circuit and provides driving signals to the brushless motor based on the three-phase control signals received from the microcontroller integrated circuit.

Description

RELATED APPLICATIONS[0001]This application claims priority to U.S. patent application Ser. No. 11 / 469,023 filed on Aug. 31, 2006, which in turned claimed priority to U.S. Provisional Patent Application Ser. No. 60 / 712,945 filed on Aug. 31, 2005 and U.S. Provisional Patent Application Ser. No. 60 / 725,775 filed on Oct. 11, 2005. The contents of all of these parent patent applications are hereby incorporated by reference in their entirety.FIELD OF THE INVENTION[0002]The invention relates generally to control electronics for brushless motors. In particular, the invention relates to the application of one or more microcontrollers to control a brushless motor.BACKGROUND OF THE INVENTION[0003]The US Department of Energy has estimated that alternating current motors consume more than 65% of the electricity produced and total electricity sales in the US will increase at an average annual rate of 1.9%, from 3,481 billion kilowatt hours in 2001 to 5,220 billion kilowatt hours in 2025. With a r...

AI Technical Summary

Benefits of technology

[0007]The preferred embodiments of the invention provide improved electric efficiency compared to conventional control electronics for brushless motors. The applications of brushless motors include air conditioners, refrigerators, power tools, washers, and dryers, and industrial power tools, such as angle grinders, to name a few. The preferred embodiments use one or more microcontrollers, which may be combined with other highly efficient components, to electronically control a brushless motor.

[0009]The control electronics according to the preferred embodiments adapt a controller IC to the challenging high power, high speed, and high performance motor application. While the controller IC may have many control functions built-in, design customization in software sets the application specific control parameters and, through both power electronics hardware and the control algorithm development, is able to efficiently achieve, for example, a maximum 30,000 rpm motor speed at 2 kW load and up to 4 kW overload capability.

[0010]Soft start is implemented to allow the motor smooth start-up and a vector control method is implemented so that the motor has much smooth torque profile. Other aspects include comprehensive control software for motor specific applications: e.g. motor start-up; under various load conditions; overload capability and protection and thermal protection—all these are achieved with a very low cost PIC processor.

Problems solved by technology

This control method has the disadvantage of fitting the hall sensors (including components and assembly costs).

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